1. Field of the Invention
The present invention relates to an improvement of an operation control device of a multi-cylinder engine arranged to be capable of controlling an air-intake individually for each cylinder with respect to each cylinder intake pipe of an automobile multi-cylinder engine.
2. Description of the Related Art
An operation control device arranged to be capable of controlling an air-intake individually for each cylinder by disposing an intake control valve in an intake passage of each cylinder of a multi-cylinder engine and controlling a valve-opening time period of the foregoing intake control valve is well known.
For example, in the Japanese Patent Publication (unexamined) No. 279698/1995 (refer to FIGS. 1 and 2) titled “Internal Combustion Engine” as described above, an intake control valve is provided individually for each cylinder, and a throttle valve operating common to all the cylinders is also provided.
In the foregoing internal combustion engine, a total air-intake is suppressed with a throttle valve when an accelerator pedal is returned due to the fact that control of a small quantity of air intake control at the time of idling operation becomes difficult only by the control of an air intake time period alone using an intake control valve performing the operation of fully closing or opening the valve.
Further, in the Japanese Patent Publication (unexamined) No. 193889/2003 (refer to FIG. 1) titled “Air Intake Control Device of Multi-Cylinder Internal Combustion Engine”, an intake control valve is provided in an intake passage of each cylinder, and an opening sensor acting to detect a valve opening of the intake control valve is also provided. Thus by controlling an intake valve opening, improvement in control of an idle engine speed is achieved such that any throttle valve common to all cylinders is not required.
On the other hand, in the Japanese Patent Publication (unexamined) No. 161194/2003 titled “Engine Control Device” relevant to the foregoing invention, the following detailed art is disclosed. This art relates, in the electronic throttle control electrically controlling a throttle valve opening, to an initial position return mechanism of a throttle valve drive mechanism, and to error determination means and non-defective determination means for an accelerator position sensor or a throttle position sensor that are displaced as a duplex system.
Both the above-mentioned Japanese Patent Publication (unexamined) No. 279698/1995 and the Japanese Patent Publication (unexamined) No. 193889/2003 adopt a type of controlling a valve-opening time period of the intake control valve. This type of intake control valve has to perform opening or closing the intake control valve at a high speed every air intake process of each cylinder. Hence a problem exits in that a large amount of power consumption of the drive control circuit is required and much deterioration of the opening/closing operation mechanism is induced, eventually resulting in a larger-sized and more expensive device to ensure a control life.
Moreover, in the above-mentioned Japanese Patent Publication (examined) No. 161194/2003, one throttle valve is provided with respect to all cylinders of a multi-cylinder engine to control a total quantity of air-intake. Therefore, a distance between the throttle valve and the intake valves of each cylinder comes to be long resulting in another problem of reduction in response of acceleration or deceleration of the engine.